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Cardiomyopathy

Cardiomyopathy is a disease that weakens and enlarges your heart muscle. There are three main types of cardiomyopathy — dilated, hypertrophic and restrictive — all of which affect your heart muscle.

What is it?

Cardiomyopathy is a disease that weakens and enlarges your heart muscle. There are three main types of cardiomyopathy — dilated, hypertrophic and restrictive — all of which affect your heart muscle. Cardiomyopathy makes it harder for your heart to pump blood and deliver it to the rest of your body. There are many causes of cardiomyopathy, including coronary artery disease and valvular heart disease. Cardiomyopathy can lead to heart failure.

Cardiomyopathy can be treated. The type of treatment you'll receive depends on which type of cardiomyopathy you have and how serious it is. Your treatment may include medications, surgically implanted devices or, in severe cases, a heart transplant.

Symptoms

Some people who develop cardiomyopathy have no signs and symptoms during the early stages of the disease. But as the condition advances, signs and symptoms usually appear. Cardiomyopathy symptoms may include:

No matter what type of cardiomyopathy you have, signs and symptoms tend to get worse unless treated. In certain people, this worsening happens quickly, while in others, cardiomyopathy may not worsen for a long time.

Causes

Most of the time, the cause of the cardiomyopathy is unknown. In some people, however, doctors are able to identify some contributing factors. Possible causes of cardiomyopathy include:

The three types of cardiomyopathy are:

Dilated cardiomyopathy. This is the most common type of cardiomyopathy. In this disorder, your heart's main pumping chamber — the left ventricle — becomes enlarged (dilated), its pumping ability becomes less forceful, and blood doesn't flow as easily through the heart. Although this type can affect people of all ages, it occurs most often in middle-aged people and is more likely to affect men. Some people with dilated cardiomyopathy have a family history of the condition.

Hypertrophic cardiomyopathy. This type involves abnormal growth or thickening of your heart muscle, particularly affecting the muscle of your heart's main pumping chamber. As thickening occurs, the heart tends to stiffen and the size of the pumping chamber may shrink, interfering with your heart's ability to deliver blood to your body. Hypertrophic cardiomyopathy can develop at any age, but the condition tends to be more severe if it becomes apparent during childhood. Most affected people have a family history of the disease, and some genetic mutations have been linked to hypertrophic cardiomyopathy.

Restrictive cardiomyopathy. The heart muscle in people with restrictive cardiomyopathy becomes rigid and less elastic, meaning the heart can't properly expand and fill with blood between heartbeats. While restrictive cardiomyopathy can occur at any age, it most often tends to affect older people. It's the least common type of cardiomyopathy and can occur for no known reason (idiopathic). The condition may also be caused by diseases elsewhere in the body that affect the heart.

Complications

Having cardiomyopathy may lead to other heart conditions, including:

Heart failure. Heart failure means your heart can't pump enough blood to meet your body's needs. The thickened, stiffened or weakened heart muscle due to cardiomyopathy can become unable to pump or can stop blood from flowing out of the heart. Left untreated, heart failure can be life-threatening.

Blood clots. Because your heart can't pump effectively, you're more likely to have blood clots form in your heart if you have cardiomyopathy. If clots are pumped out of the heart and enter your bloodstream, they can block the blood flow to other organs, including your heart and brain. If clots develop on the right side of your heart, they may travel to your lungs (pulmonary embolism). To reduce your risk, your doctor may prescribe a blood thinner (anticoagulant medication), such as aspirin, clopidogrel (Plavix) or warfarin (Coumadin).

Heart murmurs. Because people with dilated cardiomyopathy have an enlarged heart, two of the heart's four valves — the mitral and tricuspid valves — may not close properly, leading to a backward flow of blood. This flow creates sounds called heart murmurs. Heart murmurs are not necessarily harmful, but they should be monitored by your doctor.

Cardiac arrest and sudden death. All forms of cardiomyopathy can lead to abnormal heart rhythms. Some of these heart rhythms are too slow to keep blood flowing through your heart effectively, and some are too fast to allow the heart to beat properly. In either case, these abnormal heart rhythms can result in fainting or, in some cases, sudden death, if your heart stops beating.

Diagnosis

Your doctor will conduct a physical examination, take a personal and family medical history, and ask when your symptoms occur — for example, whether exercise brings on your symptoms. If your doctor thinks you have cardiomyopathy, you may need to undergo several tests to confirm the diagnosis. These tests may include:

Chest X-ray. An image of your heart will show whether it's enlarged.

Echocardiogram. An echocardiogram uses sound waves to produce images of the heart. Your doctor can use these images to examine the size of your heart and its motions as it beats.

Electrocardiogram (ECG). In this noninvasive test, electrode patches are attached to your skin to measure electrical impulses from your heart. An ECG can show disturbances in the electrical activity of your heart, which can detect abnormal heart rhythms and areas of injury.

Cardiac catheterization and biopsy. In this procedure, a thin tube (catheter) is inserted in your groin and threaded through your blood vessels to your heart, where a small sample (biopsy) of your heart can be extracted for analysis in the laboratory. Pressure within the chambers of your heart can be measured to see how forcefully blood pumps through your heart. Pictures of the arteries of the heart can be taken during the procedure (coronary angiogram) to ensure that you do not have any blockage.

Cardiac magnetic resonance imaging (MRI). Cardiac MRI is an imaging technique that uses magnetic fields and radio waves to create images of your heart. Cardiac MRI is often used in addition to echocardiography, particularly if the images from your echocardiogram aren't helpful in making a diagnosis.

Blood tests. One blood test can measure B-type natriuretic peptide (BNP), a protein produced in your heart. Your blood level of BNP rises when your heart is subjected to the stress of heart failure, a common complication of cardiomyopathy.

A variety of other blood tests may be done, including those to check your kidney function and look for anemia and thyroid problems. Your iron level may be measured. Having too much may indicate an iron overload disorder called hemochromatosis. Accumulating too much iron in your heart muscle can weaken it and cause cardiomyopathy.

Treatments and drugs

The overall goals of treatment for cardiomyopathy are to manage your signs and symptoms, prevent your condition from worsening, and reduce your risk of complications. Treatment varies by which of the major types of cardiomyopathy you have.

Dilated cardiomyopathy

If you're diagnosed with dilated cardiomyopathy, your doctor may recommend medications, surgically implanted devices or a combination of both. The medications you may be prescribed include:

Digoxin (Lanoxin). This drug, also referred to as digitalis, increases the strength of your heart muscle contractions. It also tends to slow the heartbeat. Digoxin reduces heart failure symptoms and improves your ability to live with cardiomyopathy.

Diuretics. Often called water pills, diuretics make you urinate more frequently and keep fluid from collecting in your body. Commonly prescribed diuretics for heart failure include bumetanide and furosemide. The drugs also decrease fluid in your lungs, so you can breathe more easily. One diuretic, spironolactone (Aldactone), may also be helpful in treating scarring of your heart tissue.

Another option for some people with dilated cardiomyopathy is a special pacemaker that coordinates the contractions between the left and right ventricles (biventricular pacing). In people who may be at risk of serious arrhythmias, drug therapy or an implantable cardioverter-defibrillator (ICD) may be options. An ICD is a small device — about the size of a box of matches — implanted in your chest to continuously monitor your heart rhythm and deliver electrical shocks when needed to control abnormal, rapid heartbeats. The device can also work as a pacemaker.

Hypertrophic cardiomyopathy

Your doctor may recommend beta blockers to relax your heart, slow its pumping action and stabilize its rhythm. These medications include Lopressor or calcium channel blockers, such as verapamil. Medications are often the preferred treatment for hypertrophic cardiomyopathy.

If medications don't work, you may need surgery or a medical device to treat your condition. Options include:

Septal myectomy. This is an open-heart operation in which the surgeon removes part of the thickened, overgrown heart muscle wall (septum) that separates the two bottom heart chambers (ventricles). Removing part of this overgrown muscle improves blood flow and reduces mitral regurgitation. Myectomy is used if medications don't relieve symptoms. Most people who have symptoms and undergo myectomy have no further symptoms. This type of surgery is available only in medical centers that specialize in the treatment of hypertrophic cardiomyopathy.

Septal ablation. Also called septal alcohol ablation, this is a treatment in which a small portion of the thickened heart muscle is destroyed by injecting alcohol through a catheter into the artery supplying blood to it. There are possible complications with this procedure, including heart block — a disruption of the heart's electrical system — which requires implantation of a pacemaker. The long-term success of this procedure isn't yet known, but it's becoming more commonly used.

Pacemaker implantation. A pacemaker is a small electronic device inserted under your skin that sends electrical signals to your heart to monitor and regulate your heartbeat. Surgery to implant the pacemaker is usually performed during local anesthesia and typically takes less than three hours. Pacemaker implantation is generally not as effective as surgical options, but it's sometimes used in older people who want to avoid more invasive procedures.

Implantable cardioverter-defibrillator (ICD). This is a pager-sized device implanted in your chest like a pacemaker. An ICD continuously monitors your heartbeat. If a life-threatening arrhythmia occurs, the ICD delivers precisely calibrated electrical shocks to restore a normal heart rhythm. A small number of people with hypertrophic cardiomyopathy are at risk of sudden cardiac death because of abnormal heart rhythms. In these high-risk individuals, many doctors recommend the implantation of an ICD.

Restrictive cardiomyopathy

Treatment for restrictive cardiomyopathy focuses on improving symptoms. Your doctor will recommend you pay careful attention to your salt and water intake and monitor your weight daily. Your doctor may also recommend you take diuretics if sodium and water retention becomes a problem. You may be prescribed medications to lower your blood pressure and control fast or irregular heart rhythms.

Many of the medications that doctors prescribe for cardiomyopathy may have side effects. Be sure to discuss these possible side effects with your doctor before taking any of these drugs.

Heart transplant

If you have severe cardiomyopathy and medications can't control your symptoms, a heart transplant may be an option. Because of the shortage of donor hearts, even people who are critically ill may have a long wait before having a heart transplant. In some cases, a mechanical heart assist device can help critically ill people as they wait for an appropriately matched donor. These devices, known as ventricular assist devices (VADs), can help blood circulate through your heart for months, or even years. A VAD may allow you to live outside the hospital while you wait. In some people who aren't candidates for a heart transplant, VAD therapy could be a long-term treatment option.

Prevention

In most cases you can't prevent cardiomyopathy. Let your doctor know if you have a family history of the condition. If cardiomyopathy is diagnosed early, treatments may prevent the disease from worsening.

You can help reduce your chance of heart failure by avoiding some of the conditions that can contribute to a weak heart, including the abuse of alcohol or cocaine, or not getting enough vitamins and minerals. Controlling high blood pressure with diet and exercise also prevents many people from developing heart failure later in life.

Lifestyle remedies

Your doctor may recommend adopting the following lifestyle changes to help you manage cardiomyopathy:

Quit smoking.

Lose excess weight.

Eat a low-salt diet (less than 2,300 milligrams a day).

Get modest exercise, after discussing with your doctor the most appropriate program of physical activity.

Eliminate or minimize the amount of alcohol you drink. Specific recommendations will depend on the type of cardiomyopathy you have.